A conventional probe apparatus includes a loader chamber for transferring a target object (e.g., a wafer) and a prober chamber for inspecting electrical characteristics of the wafer transferred thereto from the loader chamber. As illustrated in FIG. 9, the prober chamber includes: a mounting table (wafer chuck) 1 for mounting a target object (wafer) W thereon and being movable in X, Y and Z directions; a probe card 2 disposed to be located above the wafer chuck 1 and provided with a number of probe pins 2A; a card clamp mechanism 4 detachably fastening the probe card 2 via a card holder 3; an insert ring 5 supporting the probe card 2 via the card clamp mechanism 4; a head plate 6 supporting the insert ring 5; a docking mechanism 7 for electrically connecting the probe card 2 to a connection ring R of a test head T; and a test head clamp mechanism 8 fastening the test head T on the head plate 6. The test head T connected to the probe card 2 via the docking mechanism 7 is configured to be rotated via a hinge H provided on a side portion of the probe apparatus.
Recently, with the development of the probe card 2, there is a strong demand for a whole contact type inspection apparatus allowing a whole contact between the probe card 2 and the wafer W at a time. In the whole contact type inspection apparatus, parallelism between the probe card 2 and the wafer W is a very important factor for determining reliability of inspection. That is, if the parallelism between the probe card 2 and the wafer W is poor, the probe pins 2A of the probe card 2 cannot make a contact with the wafer W under a proper and uniform needle pressure, resulting in deterioration of inspection reliability. Moreover, the poor parallelism between the probe card 2 and the wafer W can sometimes cause damages to the probe card 2 or the wafer W.
For the reasons, various techniques for controlling parallelism between a probe card and a wafer have been proposed, and some of those techniques are disclosed in References 1 to 4.
In Reference 1 (Japanese Patent Laid-open Application No. H06-021166), a piezoelectric device is inserted into a chuck top, and a top end stage of the chuck top is slanted. Further, a DUT (Device Under Test) board having a probe card thereon is made to be slanted by using the piezoelectric device or an actuator (a rotary screw or the like). The slope of the probe card is detected by employing a non-contact type method, for example, by irradiating laser beams to the probe card. When using laser, the slope of the probe card is detected by irradiating laser beams to the peripheral portion of the probe card and detecting the heights thereof at more than two points thereon.
Further, the technique disclosed in Reference 2 (Japanese Patent Laid-open Application No. H11-251379) includes: an XY-direction driving unit for moving a wafer stage in X-direction and Y-direction; a Z-direction driving unit for moving the wafer stage in Z-direction; and a slope control unit disposed between the XY-direction driving unit and the Z-direction driving unit, for controlling a slope of the wafer stage with respect to a horizontal plane. When controlling the slope of the wafer stage, tip heights of four probe needles located on four corners of a probe card is detected by using a self-focusing camera, and the slope of the probe card with respect to the wafer stage is calculated based on differences between the detected tip heights.
Disclosed in Reference 3 (Japanese Patent Laid-open Application No. H07-231018) is an invention including: a contact-type displacement sensor for detecting tip heights of probe needles at plural locations on a probe card; a detection circuit for detecting a voltage variation of the displacement sensor; a control system for calculating slopes and slope directions of tip heights of the probe needle group based on the detection result from the detection circuit and outputting an instruction for correction; and a slope correction unit supporting an insert ring at three points and serving to correct the slopes of the tip heights of the probe needles by varying the supporting heights of the insert ring at the three points of the insert ring individually. In this configuration, after detecting tip heights of the probe needles at the plural locations (e.g., four locations in left-and-right and back-and-forth directions) on the probe card, slopes and slope directions of the tip heights of the probe needle group are calculated by using calculation software stored in a control system in advance. Further, in addition to the slopes of the probe needles, the slope of a wafer can also be measured, in which case the slope correction can be performed based on the two data. Moreover, Reference 4 (Japanese Patent Laid-open Application No. H08-162509) also discloses a technique for adjusting the slope of a wafer chuck, which is similar to the method described in Reference 3.
Though References 1 to 4 disclose various methods for adjusting a parallelism between a probe card and a wafer stage, those methods are all directed to measuring tip heights of a probe card or heights of the probe card at plural points thereof, calculating a slope of the probe card based on the measurements; modifying the slope of one of the probe card and the wafer stage to be made identical with the slope of the other, to thereby adjust the parallelism therebetween. However, any of those techniques in References 1 to 4 does not clearly disclose any specific method for adjusting the parallelism between the probe card and the wafer stage, and if any, the method requires a high level of skills or takes up much time.